The present invention relates to a bumper assembly for vehicles having an improved reinforcement member made of a metal.
In order to alleviate impact on a passenger or decrease a damage of a vehicle body in collision, a bumper assembly is attached to a front portion of a vehicle. One example thereof is disclosed in, for example, Japanese Patent Laid-Open Publication No. Hei 4-303046/1992. According thereto, as shown by FIG. 7, there is constructed a basic structure in which a hollow reinforcement member (bumper reinforcement) 2 made of a metal having a section substantially in a rectangular shape and extended in a width direction of the vehicle, is fixed to each of side members 1 on both sides of a front portion of the vehicle.
An absorber 3 comprising a urethane material and a bumper cover 4 constituting an exterior of the vehicle are arranged at a region frontward from the reinforcement member 2. The bumper cover 4 is fixed to the reinforcement member 2 and a cover supporting member 7 by using bolts or clips 5 and 6.
According to the example shown by FIG. 7, holes are perforated at a rear wall portion of the reinforcement member 2 and energy absorbing members 8 are arranged at inside of the reinforcement member 2 via the holes. The energy absorbing member 8 is constituted in a shape of a pipe comprising an aluminum alloy or a fiber reinforced resin and press-inserted into the hole of the reinforcement member 2. A front end thereof is brought into contact with a front wall portion of the reinforcement member 2 and a rear end thereof is brought into contact with a front face of the side member 1.
When impact is applied on the bumper assembly in collision of the vehicle, the reinforcement member (bumper reinforcement) 2 is deformed. According to the deformation of the reinforcement member 2, an upper wall portion and a lower wall portion are deformed to buckle toward outer sides such that the front wall portion becomes proximate to the rear wall portion and the energy absorbing members 8 are compressed to deform in a bellow-like shape. Thereby, as shown by FIG. 8, there is provided a characteristic of an energy absorbing amount (E/A amount) indicating a long and low displacement region and a high yield load A.
According to the conventional bumper assembly, as shown by FIG. 8, although there is observed rapid energy absorption caused by buckling the reinforcement member, thereafter, regardless of adding the energy absorbing members, there is indicated the long and low displacement region and the energy absorbing function is not high.
Further, there are needed the energy absorbing members other than the reinforcement member and accordingly, a number of parts is increased, which is disadvantageous in view of the cost and in view of the productivity.
According to the deformation of the reinforcement member, the upper wall portion and the lower wall portion are deformed to buckle on the outer sides and therefore, there is a concern that the deformation interferes with functional parts (head light, winker lamps and so on) other than the bumper assembly and destruction thereof is caused, which is not preferable.